I have a dockerized postgres 9.3.5 OLTP instance that I’m going to update to 9.5.2. Instead of shutting it down and doing a pg_dumpal to a file and then load it I would like to spin up a new docker container and pipe the database pg_dumpall -h localhost -p [port] -U postgres | psql -h localhost -U postgres -p [port]. I’m thinking I could alter the postgresql.conf to be in read only mode. This would temporarily mess with my app but at least users could still SELECT. Is there a better way to go about this? Are there any big issues with putting in read only mode while I pipe the database over?